1. Field of the Invention
The present invention relates to a torque transmission system of the type which utilizes driving and driven pulley units and an endless V-belt to transmit the torque of a shaft to another shaft. The transmission system of the present invention can be used, for example, to transmit the torque of an automotive engine to an auxiliary rotary devices or accessories, such as air pump, water pump, fan, compressor, alternator or the like.
In co-pending U.S. patent application Ser. No. 140,594 filed by Hattori et al on Apr. 15, 1980, there is disclosed a torque transmission system having driving and driven pulley units drivingly connected together by an endless V-belt. Each of the driving and driven pulley units has a stationary pulley rotatable with a shaft and a movable pulley disposed to define with the stationary pulley a circumferentially continuous groove for receiving the V-belt. The movable pulleys of the two pulley units are axially resiliently biased so that the radii of the circles along which the V-belt engages the driving and driven pulley units are varied to change the speed-change ratio of the transmission system. The driven pulley unit includes fly weights which are rotatable with the movable pulley of the driven pulley unit and centrifugally displaced radially outwardly to axially shift the movable pulley. The driving and driven pulley units are provided with cam mechanisms each comprising a cam member and a follower member. When the load on the driven pulley unit is suddenly varied, the cam mechanisms are operative to keep the rotational speed of the driven pulley unit constant irrespective of variation in the load on the driven pulley unit.
2. Summary of the Invention
The present invention has its object to provide an improved power transmission system.
The power transmission system according to the present invention comprises a shaft; a stationary pulley part fixed to said shaft; a movable pulley part disposed in axially opposite relationship to said stationary pulley part and movable in the axial direction along said shaft toward and away from said stationary pulley part to vary the width of a belt-receiving groove formed between said stationary and movable pulley parts; a V-blet received in said belt-receiving groove; a holder fixed to the side of said movable pulley part opposite to the side thereof which is contacted by said V-belt, said holder having an inclined surface extending obliquely with respect to the axis of said shaft; a stationary plate fixed to said shaft and disposed axially outwardly of said holder; at least one fly weight held between said stationary plate and said holder; a cover disposed axially outwardly of said stationary plate and covering the same, said cover cooperating with said stationary plate to define a first space therebetween, said stationary plate cooperating with said movable pulley part to define a second space therebetween, said movable and stationary pulley parts cooperating together to define a third space therebetween; means for communicating said first, second and third spaces with the atmosphere to maintain said spaces substantially at the atmospheric pressure.
The communication means may preferably comprise a first communication port formed in the stationary plate to provide a communication between the first and second spaces, an axial bore formed axially in the shaft to provide a communication between the first space and the atmosphere and a second communication port formed substantially radially in the shaft to provide a communication between the third space and the axial bore. The first communication port may preferably be formed in the stationary plate adjacent to the shaft.
As mentioned above, the first to third spaces in the torque transmission system according to the present invention are communicated with the atmosphere and, therefore, are maintained substantially at the atmospheric pressure regardless of the changes of the volumes of the spaces due to axial movements of the axially movable members. Accordingly, the transmission system can advantageously be free from any adverse effect which would otherwise be caused by the compression of air in the mentioned spaces when the volumes of these spaces are reduced.
The above and other objects, features and advantages of the present invention will be made apparent by the following description with reference to the accompanying drawings.